Portable theodolites, or transits as they are commonly known, are used throughout the construction, carpentry and surveying trades as well as in other applications. The devices generally include a stand, such as a tri-pod to which the theodolite is pivotally mounted upon a top surface thereof for rotation about a horizontal and/or vertical axis. In operation, the devices are generally leveled manually using thumbscrews and the like in combination with fluid filled sight type level gauges. The theodolite generally includes a telescope in which cross hairs are positioned in the line of sight for use as a visual reference, allowing the person looking through the telescope to utilize the instrument for leveling and the like.
For example, U.S. Pat. No. 1,429,437, discloses a Convertible Builders Level and Transit. The device includes a base plate having a pair of mounts for a theodolite. The theodolite may be mounted in one position for upward movement and a second position for leveling.
U.S. Pat. No. 1,533,545, discloses a Convertible Level and Transit. The device includes a tripod which has a threaded stud for attachment to a leveling plate. The upper face of the plate includes a rounded boss upon which the base plate is mounted. The base plate includes leveling screws for leveling the theodolite device with respect to the ground surface. The base plate includes upstanding Y-forks upon which the theodolite may be mounted for upward pivoting in one position and fixed for leveling in a second position.
It is also known to provide an automatic leveling device in combination with a theodolite, to eliminate the manual leveling requirement. For example, U.S. Pat. No. 3,663,111, discloses a Self Leveling Transit Having a Locking Mechanism. The device includes a telescope incorporating therein an automatic level line compensator and means for locking the swinging portion of the compensator means. The telescope may be used as a transit when the lock is operative to lock the swinging portion of the telescope, and as a level when the lock is not in operation.
Laser technology has also been utilized for indicating a level reference plane. Within these devices portable laser emitters are used in place of the theodolite telescope to establish the reference plane. In the construction industry, narrow beams of collimated light, in the form of laser beams are being increasingly used in connection with establishing and marking long, straight, level lines, such as those required for markings for walls, ceilings, and/or floors. Also, laser beam projectors and receivers are often used in the construction industry and in agricultural land leveling applications to ensure that a target area is graded in the proper or desired slope or grade. The laser beam projector is placed in a known position and one or more sensors are placed in the targeted area to sense the impingement of the laser beam.
These devices generally include a laser source for generating a beam of collimated light and a rotating mechanism for rotating the beam of light about an axis to generate a plane of light. In order to provide a substantially level plane, it is necessary to have a known orientation for the laser plane with respect to the true earth reference. Typically, the laser plane is oriented into a level position with respect to the supporting surface, such as by manually leveling the mechanism, or by a self-leveling gyroscopic or magnetic mechanism. Additionally, some laser plane generators are operable to orient the laser plane at an angle with respect to a level orientation by rotating the laser generator about a desired axis according to the desire slope.
For example, U.S. Pat. No. 3,471,234, discloses a method and apparatus for performing precise surveying operations relative to a selected reference point by utilizing a laser beam. A portable laser beam reference plane generator is provided which may be set up in precise alignment with a selected reference point, and which produces a rotating laser beam sweeping over the adjacent terrain. The generator may be accurately adjusted to permit both elevation and angular displacements to be measured at any point within the area traversed by the rotating laser beam.
U.S. Pat. No. 5,394,616, discloses a Laser Positioning Device. The device includes a level having a pair of magnetic feet mounted thereto and a plate member mounted to one side to extend upwardly therefrom. The plate member is scribed with protractor markings for angular measurement. A pointer is pivotally associated with the apex of the protractor to which a laser beam generator is mounted. In operation, a laser beam from this generator can be impinged against a remote target location and an angle measurement may be taken from a known datum using the protractor.
U.S. Pat. No. 5,983,510, discloses a Three-Dimensional Laser Leveling and Angle-Calibrating Instrument with Multiple Functions. The device includes a stand and a pair of magnetically attachable laser levels. The stand includes a horizontal and a vertical plate to which the magnetic laser levels are attached. This construction permits one laser level to be used for horizontal leveling while the other is used for vertical leveling.
U.S. Pat. No. 3,823,313, discloses a Laser Fanning Device. The device includes a laser generator mounted on a conventional transit for rotation about a vertical axis. A crank is interconnected at one end to the support structure of the transit and at its other end to the drive of an electric motor affixed to the transit and laser generator. Operation of the motor and crank causes rotational and reciprocal movement of the transit and generator about an axis to develop a datum plane of light. A control knob provides grade adjustment and is linked to a digital counter to provide a visual readout of the grade.
While such laser projectors facilitate generating a laser plane at a desired grade and orientation, the higher number of moving parts, including the rotating mechanism, within the laser projector may raise reliability concerns over a prolonged period of time. Also, when sensors are not used to sense the laser beam, the reference plane generated by the rotated laser beam can be difficult to see with the human eye as the beam of light is intermittently flashed along a surface.
It is also known to combine a distance measuring instrument with a theodolite. For example, U.S. Pat. No. 3,874,087, discloses a Surveying Instrument. The device includes a theodolite and an electro-optical telemeter in which the transmitter and receiver of the telemeter are arranged in gravity-symmetrical relationship with respect to the horizontal axis of the theodolite. The transmitter and receiver are housed within a U-shaped body having a hole through which the theodolite fits. The device is held in place by dovetails mounted on the upper surface of the theodolite.
U.S. Pat. No. 4,305,209, discloses an Adaptor for mounting one instrument, such as an electronic distance measuring device, atop another instrument, such as a telescope or theodolite. The device includes a base member attached to the upper device. The base member includes two downwardly facing cam surfaces and support members engaging the cam surfaces for vertical movement against springs to counteract the forces produced by the upper instrument as it pivots while the device permits the two devices to be moved together about a horizontal axis.
U.S. Pat. No. 3,874,087, discloses a Surveying Instrument. The device includes a theodolite and an electro-optical telemeter in which the transmitter and receiver of the telemeter are arranged in gravity-symmetrical relationship with respect to the horizontal axis of the theodolite. The transmitter and receiver are housed within a U-shaped body having a hole through which the theodolite fits. The device is held in place by dovetails mounted on the upper surface of the theodolite.
As disclosed, the above devices fail to teach or suggest a theodolite having a telescope in combination with a laser emitter. The prior art is also deficient in teaching a theodolite having a laser positioned to project a laser beam along the centerline of the line of sight of the theodolite telescope for use as an external reference for marking the instrument line of sight. The prior art is also deficient in teaching a kit for fitting a new or pre-existing telescope type theodolite/transit with a laser indicator.
Accordingly, the instant invention provides a theodolite in combination with a laser emitting device. The instant invention provides optical indication through the theodolite telescope as well as external visual indication (a laser beam) along the centerline of the telescope line of sight. The instant invention also provides a kit for fitting a new or pre-existing theodolite with a laser indicator. The laser theodolite kit includes adaptability for installation on various theodolite configurations which may include theodolites with auto-focus or auto-leveling.